SOLUTION: A discrete random variable X has probability mass function P(x) = a(2/5)^x, x=0,1,2,3... Find the value of a.

Question 1189201: A discrete random variable X has probability mass function P(x) = a(2/5)^x, x=0,1,2,3... Find the value of a.
Answer by ikleyn(52797) (Show Source): You can put this solution on YOUR website!
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The sum of the infinite geometric progression  P(0) + P(1) + P(2) + . . .  must be equal to 1.  It gives an equation to find "a".


The sum is equal to   =  = .


So,   must be equal to 1


     = 1,


which gives  a =  = 0.6.    ANSWER

Solved and explained.

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